Chair base



FIG. 1 is a left front perspective view of a chair base showing my newdesign;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof, the left sideelevational view being the mirror image thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a left, front perspective view of a chair base showing amodification of my new design;

FIG. 8 is a top plan view of the chair base of FIG. 7;

FIG. 9 is a front elevational view thereof;

FIG. 10 is a right side elevational view thereof, the left sideelevational view being the mirror image thereof;

FIG. 11 is a rear elevational view thereof; and

FIG. 12 is a bottom plan view thereof.

The broken line showing of a seat member in FIGS. 1 and 7 is forillustrative purposes only and forms no part of the claimed design.

The ornamental design for a chair base, as shown and described.